Vacuum discharge tube



July 10, 1934. A. MUTSCHELLER VACUUMI DISCHARGE TUBE Filed'Jan. 3, 1930 Patented July 10, 1934 PATENT@ OFFICE VACUUM DISCHARGE TUBE Arthur Mutscheller, New York, N. Y., assignor to Wappler Electric Company, Inc., Long Island City, N. Y.

Application January 3, 1930, Serial No. 418,178

7 Claims.

The principle of my invention is outlined in my earlier Patents No. 1,738,959 and No. 1,738,960 of December 10th, 1929, and applications, Serial Number 210,489 led August 4th, 1927 and Serial 5 Number 210,488 filed August 4th, 1927. However, in the application of this principle I have succeeded in producing still further improvements which result in a device that embodies the following advantages: l-greater electrical capacity than the older devices,

Z-easier evacuation, 3-considerably simplified glass-technical construction,

d-greater robustness in use and -simplified methods of cooling of the devic while in use.

Fig. 1 represents a simple type of the device illustrating the underlying principle. Fig. 2 is a more practical and more emcient construction.

Fig. 3 is a section of the same construction along the dotted kline III-III of Fig. 2, Ylooking in the direction of the arrows. Fig. 4 is still another construction making use of the same principle. Y

My invention, vas outlined in my earlier applications, is based upon the fact that if, upon a metallic cathode heated to incandescence, a positive electric field is concentrated, this results in a pulling out effect upon the electrons in the cathode which gives rise toan increased emission of electrons from the cathode. Stillfurther it is pointed out that if an intensiiied negative electrical field is produced in back of the cathode, then this fieldY exerts a pushing out eifect upon the electrons in the direction away from the cathode. In the present invention there is a novel way employed of combining these two effects re- 40 sulting in a high voltage rectier of a maximum of eiiiciency and embodying the advantages already outlined over the devices for similar purposes hitherto known. Y

In Fig. 1 is shown an anode 1 consisting of a spun or cast spherical ball made of copper, iron,

platinum, molybdenum, tantalum, etc., or any of the metals used in the vacuum technic. Fused on to it is a glass sleeve 2 which is inverted and which in its central tubular portion 3 carries two wires 4 and 5 electrically separated for supplying heating current to the glower cathode 7. vAt the outer end theseheating wires areV fastened to a conventional socket 6 by means of which they can be connected conveniently to a source of heating current, that can be regulated as Vcentrated in the center.

(Cl. Z-27.5)

is required and well understood in this art. The cathode 7 consists of a loop of wire or ribbon, consisting of a refractory metal that can be heated in a vacuum to a high temperature and which may be supported as is shownby an insulated post 8 or by other suitable means.

In this case the cathode is shown as a loop concentrically placed within the spherical anode. This is for the purpose of illustrating the principle of my invention for which the cathode is shown in one plan instead of in spherical dimensions.

It is well known in the electrical art that a charge distributed over a sphere acts as if concentrated in the center of the sphere. Therefore, by placing a cathode into the center of a spherical anode, the positive electrical eld at the anode is concentrated upon approximately the center of the sphere. Therefore, by placing the cathode in the form of a small sphere into the center of the large spherical anode as accurately as this can be done, there is obtained a concentrating effect of the positive eld from the large anode upon the smaller cathode disposed in the center of the spherical anode. The result is that Athe electrons` are attracted and pulled out of the hot cathode and there is an electronic discharge current, which is larger than the pure thermo electronic discharge current, as for example represented by the well-known Richardson equation.

Moreover, by forming and shaping the cathode such that its active electron emitting parts do not occupy exactly the center of the anode but that its active portions are located upon the surface of a sphere, a similar concentrating effect is obtained with respect to the force of a negative eld upon the electrons set free from the cathode.

A negative charge distributed over the cathode will, therefore, again act as if located and con- Hence, in the center of a spherical cathode there will be localized an intensive negative eld which exerts a distinct pushing out effect upon the electrons liberated from the cathode.

However, the positive iield, although ordinarily acting as if concentrated in the center of the spherical anode, will be prevented from being so concentrated by the electron emitting portions of cathode which are located upon the surface of the spherical cathode. The positive field consequently is stopped or decreased so that the electrons will not travel towards the center of the anlOO ode, but travel from. their origin outward; being ,mutually repelledfrom one another, and, therefore, having a direction component towards the anode. On the other hand the negative field will act as if concentrated in the center of the cathode and there will be exerted from its center a pushing out of electrons in a radial direction which augments the pulling out eiect exerted by the positive eld.

By thus combining the pulling effect resulting from a large anode disposed spherically around the cathode with the pushing out eifect from a spherically arranged negative charged cathode,y

an electron emission is obtained which is considerably larger than that resulting from the thermionic emission alone which exceeds as before stated that represented by the well known Richardson equation.

Fig. 2 shows a practical method of producing a cathode for large emission as is required for instance in a high voltage valve tube for rectify` ing high voltage alternating currents of a magnitude of up to 10 or 20 amperes. 'Io the conducting wires 11 and 12 is welded or soldered on a lament 13 of tungsten, tantalum either metallicr or coated to increase its emission. This iilament passes through a block of refractory insulating material 14 provided with holes through which the wire may pass. To prevent heating of these portions of the lament, there are pushed in alongside of it other pieces of wire making contact lengthwise with the iilamentary wires and so carrying part of the current. Still another method consists in passing the filament wire through short metallic tubes.

These filaments 13 may be round wire or ribbon. Preferably they are hammered or pressed flat toa V-shaped cross section, as is shown in Fig. 3. In this form the thin portion tends to heat more than the thicker portions of the wire and the larger emission is then from the sharp edge.

Again another method of arranging the iilamentary cathode is shown in Fig. 4. Here 15 is a small ball or sphere of refractory insulating material. -Equidistant therein are drilled small holes as sectors from one place on the surface to a place only one or several millimeters apart. Through these holes the cathode wiremay be passed and bent to form V-shaped or loop shaped points Vwhich are heated by the passage of current and which are located equidi'stant from aV common center. The ball of insulating material is suitably supported by a stem 16.

Furthermore, when the condition is reachedy which commonly is referred to as voltage saturation in the electron discharge devices of the prior art, it is found that a saturation condition, as previously understood, does not exist in a discharge tube of my construction. Thus, when the electron emission from the cathode has grown to the stage when all the electrons which are freed from the cathode due to its temperature, are pulled over by the voltage eld to the anode, then the combined pushing and pulling out effect added, which is due to a voltage between the cathode and the anode, sets in, then the electronic discharge continues to increase further in proportion as the voltage increases between the anode and the cathode. Instead, therefore, of giving a discharge characteristic represented by a curve that has a sharp bend, the discharge characteristie is an almost regularly bent curve which never becomes a straight line.

I 'desire in particular to call attention to the cated either inside of a glass bulb or the outer wall of which may be exposed to the atmospheric air, can be cooled by various means Well known in this art. So, for instance, the anode can be cooled in water or it can be developed into the form of a radiator which, through air circulation, either natural or forced, can be kept cool so that the usual limitations in current carrying capacity and in heat developed are thus easily rendered harmless. This is particularly of importance when considering the fact that a difference of potential between the electrodes, which increases the discharge between them, Would gradually also result in an acceleration of electrons with accompanied heating of the anode due to their impact upon the anode.

On the other hand, the anode, being on one side freely lexposed to the free air, can also be heated by applying heat externally during the pumping process to free it of gas, which process, in my construction, is much easier carried out than with the discharge devices of the prior art.

The previous remarks refer to potential differences when the cathode is negative and the anode positive. If, however, the polarity is reversed and the anode becomes negative against tively blocked than in the case when there is no such field intensification; While, therefore, at correct discharge polarity the emission of electrons is increased over Yor above the usual thermionic discharge so by the same principle, when the polarity is reversed, there is an increased valve action. From this results, that the discharge device herein described not only is capable of passing and rectifying larger volumes of current than the devices of the priorV art, but also that it is capable of stopping or rectifying considerably higher voltages than the devices heretofore known.

Having thus described several forms of my invention, I do not limit myself to either one or the other Vof these specic forms, but these are simply used to explain the theory or principle of the broad scope of mydiscovery.

I claim:

1.V A'highly evacuated discharge device consisting of van inverted sleeve of insulating material carrying onone end a sphere shaped metal anodeand onV the other end a smaller sphere shaped double terminal cathode concentric with said anode, said cathode consisting of V-shaped portions located symmetrically and equidistantly from a common center.

2. An electron discharge device comprising an inverted sleeve of insulating material, a multifilament cathode secured to one end of said sleeve with the electron emitting portions thereof peripherally disposed relative to a common axis for concentrating an electric field in back of the multi-filament cathode, and an anode secured to the remaining end of said sleeve and forming therewith an evacuated envelope, said anode being spaced uniformly from all the peripherally disposed electron emitting portions of said cathode.

3. An electron discharge device comprising an inverted sleeve of insulating material, a multilament cathode secured to one end of said sleeve of substantially spherical form with the electron emitting portions thereof peripherally disposed to cause a concentrated electric field about the center of said spherical formed cathode, and a spherical shaped anode secured to the other end of said sleeve and forming therewith an evacuated envelope, said anode being concentrically disposed relative to said cathode for increasing the intensity of the electric eld concentrated about said cathode to cause an increase in the electron emissivity of said device during operation thereof.

4. An electron discharge device comprising an inverted sleeve of insulating material, a multifilament cathode secured to one end of said sleeve having its active electron emitting portions peripherally disposed relative to a common center to cause a concentration of the electric field about the common center of said cathode, and a spherical shaped anode secured to the remaining end of said sleeve and forming therewith an evacuated envelope, said anode having a surface coacting with the electron emitting portions of said cathode during operation of said device and spaced uniformly therefrom to cause an increase in the intensity of the electric eld about said cathode and an increase in the electron emissivity thereof.

5. An electron discharge device comprising an inverted sleeve of insulating material, a double terminal fllamentary cathode secured to one end of said sleeve having its active electron emitting portions peripherally disposed relative to a common center to cause a concentration of the electric eld about the common center of said cathode and an increase in the'electron emissivity of said cathode, and a spherical shaped anode secured to the other end of said sleeve and forming therewith an evacuated envelope, said anode surrounding said peripherally disposed electron emitting portions of said cathode and uniformly spaced therefrom to produce a field about said cathode cooperating with the eld concentrated about the common center thereof to cause an increase in the electron emissivity of said cathode during operation of said device.

6. An electron discharge device comprising an inverted sleeve of insulating material, a double terminal spherical shaped cathode secured to one end of said sleeve having its active electron emitting portions peripherally disposed relative to a common center to cause a concentration of a negative electric field about the common center of said cathode, and a spherical shaped anode secured to the remaining end of said sleeve and forming therewith an evacuated envelope, said anode being concentrically disposed relative to said spherical shaped cathode to produce a concentrated positive electric field about said cathode cooperating with the negative electric eld concentrated at the center of said cathode to increase the electron emissivity of said cathode during operation of said device.

7. An electron discharge device comprising an inverted sleeve of insulating material, a double 100 terminal cathode secured to one end of said sleeve having a plurality of active electron emitting portions projecting outwardly and peripherally disposed relative to a common center to cause a concentration of a negative eld about 105 the center of said cathode, and a spherical shaped anode secured to the other end of said sleeve and spaced uniformly from all outwardly projecting electron emitting portions of said cathode to produce a concentrated positive electric field about 11() said cathode cooperating with the negative electric field concentrated at the center of said cathode to increase the electron emissivity of said cathode during operation of said device.

ARTHUR MUTSCHELLER. H5 

